Abstract

Thermotolerant Coliforms (TtC) bacteria is one of the microbial quality indicators of drinking water. This study was
aimed to Survey of Effective parameters (Water Resources, Seasonal Variation and Residual Chlorine) on Presence
of thermotolerant bacteria in drinking water. For this study, data of the last 10 years assessments of microbial quality
regarding various species of fecal coliform was taken from health centers associated with urban, rural and private
sources of Kermanshah city. A total number of 8643 samples were taken, 1851 samples from rural, 365 from urban
and 4834 from private resources.
The results showed that fecal coliform, Escherichia coli (22.3%) and Klebsiella (2%) were the most and least bacteria
existent in urban water resources, respectively. In rural water sources, E. coli (45.9%) and Enterobacter cloacea
(2.6%) and in private sources E. coli (34%) and Klebsiella (1.3%) had the most and least existent, respectively.
Further, E. coli (47.5%) and Klebsiella (0.4%) had, respectively, the highest and lowest distribution in all months
considered. In addition the results showed a significant decrease of distribution of fecal coliforms with increasing
residual chlorine, while a decreasing trend is observed from the dose of 0.8 mg/L. According to the results, it can be stated that among fecal coliforms, E. coli has the widest distribution in water resources and because this bacterium causes diseases such as diarrhea and hemolytic uremic syndrome, so is of particular importance in the monitoring of water resources. Hence it is necessary to consider the bacterium in resources with low microbial quality, especially in
the hot seasons.